Process of producing thickened lubricating oil



; inum soap so Patented Nov. 113, i928.

UNITED STATES earner ROBERT W. HENRY, 01 PORT ARTHUR, TEXAS, AND ELFORD D. STREETEB, OF BA- YONNE, NEW JERSEY, ASSIGNORS TO GULF REFINING COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF TEXAS.

PROCESS OF PRODUCING THICKENED LUBRICATING OIL.

No Drawing.

This invention relates to process of producing thickened lubricating oil; and it comprises a method of producing an improved lubricating oil of the type sometimes known as mineral castor oil and consisting of lubricating oil containing a dissolved or dispersed basic aluminum oleate or other basic alum num soap wherein an aluminum soap of bas c nature is produced by alkalizing a less bas c aluminum soap, and removing or reprecipitating the water soluble soap formed; all as more fully hereinafter set forth and as claimed.

In the art what are known as mineral castor oils or castor machine oils are extensively made by thickening mineral lubricating oil by an addition of a certain amount of aluminum oleate. This oleate is ordinarily a trioleate; that is, each atom of aluminum is combined with three oleic acid groups. These trioleate preparations are generally made by direct precipitation of a solution of sodium oleate by an aluminum sulfate solution 1n the proper proportions.- The preclpitated alummade is separated from the mother liquor, which is a solution of sodium sulfate, washed, dried and added to the mmeral oil to be thickened. The oleate goes into solution or dispersion and gives a great increase in viscosity; the result wanted. In the usual types of mineral castor 011, however, this increase is neither regular nor constant. In adding a given quantity of oleate to a given oil, the exact increase in vlscos ty is uncertain and the viscosity ust after 1ncorporation is by no means what it is after the thickened oil has been allowed to stand for a time and age. There is always a marked drop in viscosity. In United States Patent 1,550,608 is described a castor oil prep aration free of the noted disadvantages; this preparation being made with basic oleates in lieu of the trioleate. Aluminum combines with oleic acid to form three different oleates which may be represented, using the symbol R to represent the oleic acid group, as, respectively, the trioleate AIR the dioleate AlR OH and the monoleate Al(OH) R. In

the stated patent, it is pointed'out that constant preparations may be obtained by the use of basic oleates; oleates containing less oleic acid than the trioleate. The patent describes a ratio between R and A1 of 1.7: 1' or 1.8 1 as being most advantageous.

Application filed March 24, 1926 Serial No. 97,116.

It is the purpose of the present invention to provide a method whereby various mixtures of metallic oleates may be produced; the mixture, however, as a whole always being more basic than corresponds to the trioleate; mixtures, for example, of trioleate and monoleate, of trioleate and dioleate, of di-oleate and monoleate, and of trioleate, dioleate, and monoleate. In the direct precipitation of a solution of sodium oleate by a solution of aluminum sulfate, which is the usual way of making aluminum oleate, the tendency is to form a trioleate. In usin the calculated quantities of aluminum sulfate and of soap for precipitation, the solution generally becomes acid to phenol-phthalein before reaction is complete because of carrying down adsorbed sodium oleate. In practice therefore, it is the custom in precipitation to use an excess of aluminum sulfate or alum and the result is the formation of trioleate. As stated, the trioleate is the substance generally used commercially in making thickened mineral oils or castors.

In the present invention, the purpose is to make a basic oleate by a precipitation-hydrolysis method, using solutions of sodium soap,'of caustic soda, and of aluminum sulfate. The composition of the final product depends upon the relative amounts of these solutions taken, and upon the procedure followed. The general methods may be as follows. In one procedure, an aluminum trioleate is formed by the action of an excess of aluminum sulfate upon sodium soap solution,

as just described, and then the requisite amounts of caustic soda solution and aluminum sulfate solution, necessary to produce a basic oleate of predetermined basicity, are i added to the aluminum trioleate portionwise and in alternation, the final addition belng of aluminum sulfate. The mechanism of t-he reaction is hereinafter explained. In anits average composition isthat of a dioleate.

This condition will be readily apparent to not enough to replace two-thirds of the oleate present in combination with the aluminum. It may be assumed that, initially, all of the trioleate is converted to dioleate, and that the excess caustic soda effects further hydrolysis to the monoleate to the extent that it is available. Substantially all of the sodium soap thus liberated in solution is then removed by decantatio n so that the final product contains aluminum monoand dioleates with little or no trioleate. Generally,

the stated operations are carried on in the I presence of a body of the mineral oil to be used in forming the final castor; that is, the work is done with emulsions rather than with simple solutions. The use of mineral oil and working in the emulsion form, however, while advantageous, is not necessary. Such mineral oil may be added at any stage of the operation prior to the last addition of aluminum sulfate, but we usually add it in the beginning. Near the end of the last addition of alum the solution becomes acid, the emulsion breaks and the aluminum soap-oil composition agglomerates into a pulp floating in a clear aqueous liquid containing sodium sulfate in solution.

In a general way, it may be said that the trioleic soaps when admixed with ordinary lubricating oils of various grad-es give castors of relatively low viscosity, decreasing greatly on aging and sensitive to heat. Qastors formed with dioleic soaps have a high initial viscosity, are adhesive, relatively insensitive to heat and of generally desirable properties, except that there is some decrease in viscosity on aging. On the other hand, castors "formed from mineral oil and monoleic soaps, while havinga high initial viscosity, become much more viscous upon aging and are; relatively non-sticky and nonstringy. Mixtures of two or more of these aluminum soaps exhibit properties, when admixed with mineral oils which are the mean of the components. In making such mixed aluminum soaps, a basic aluminum soap and a less basic aluminum soap may be made separately, and then mixed to form a product having the desired ratio of fatty acid to aluminum. On the whole, we find best for the R, as before, indicating a molecule of oleic acid or any other fatty acid, but advantageously oleic acid or an unsaturated oily fat acid. The best results are obtained within the range OH R and OH R which expressions are, of course, arbitrary representations of the percentage composition of the mixture of two or more aluminum oleates of different basicities.

In practical embodiments of the present invention, while we can use a commercial soda soap as a starting material, we usually make a soap specially for the present urposes, preparing a neutral soda soap wit 1 the use of cottonseed oil orany other fatty oil. These oils, of course, contain glycerids of other fatty acids than oleic acid, but for the present purposes these acids are equivalent. The unsaturated acids of the oleic type are, however, better than the saturated. Corn oil works about as well as cottonseed oil. Stearic acid, oleostearine, cocoanut oil, and mixtures of these products with cottonseed oil are usually less satisfactory. Commercial oleic acid generally contains too much iron as an impurity, althoughit gives desirable products otherwise. In saponifying oil, the reac- IOU tion is usually incomplete unless an excess of caustic soda is used. Thus the soap solution will usually contain free caustic. Any such excess alkali, we afterwards neutralize with free fatty acid. It is best for our purposes to have a soap neutral to phenolphthalein when tested in alcohol. The neutral soap solution we usually emulsify with mineral oil of the same character as that to form the body of the final castor. l/Ve generally employ a volume of mineral oil about twice that of the original cottonseed oil. The oil emulsifies readily, giving an oil in water emulsion; the water solution containing the soap. In a practical application of the present invention, we start with about 750 pounds of cottonseed oil, and add 15 Baum caustic soda solution in amount insuflieient to saponify the oil. The mixture is stirred and blown with air for 3 or 4 hours and allowed to stand over night. The soap solution is then boiled and stirred or blown with steam for about an llOlllQflftBI which small amounts of suitable fatty acid, such as a good grade of red oil, are added until a test in alcoholic solution shows no color with phenolphthalein; indi cating neutrality of soap. To this mixture is added 150 gallons of mineral oil and stirring is continued until the whole is emulsified and eereea sulfate contains an excess of acid this excess should be neutralized by an addition of caustic soda. on the other hand, the aluminum sulfate solution may contain an excess of alumina, in which case a correspondingly less amount of caustic soda is used in the step following. This addition of alum solution gives a soap approximating the trioleate; the

trioleate containing adsorbed sodium oleate, and being suspended in slightly alkaline solution. In an alkaline medium, the pulp does not agglomerate and the precipitates are in convenient physical form. ln this embodiment of the invention, sodium soap is in exccss and the solutions are alkaline up to the addition of alum.. We next add slowly caustic soda solution in an amount equivalent to "66.5 pounds of NaOH. If the alum solu tion contains excess of alumina, as indicated above, an amount of llaOH corresponding to this basicity is deducted from the indicated quantity of 66.5 pounds of NaQH. The caustic soda addition re-forms sodium oleate at the expense of the aluminum trioleate and produces aluminum monoleate. After the caustic soda has been added, the stirring is continued for a time until a test (in alcoholic solution) shows no free caustic, or alkalinity. We next slowly add more alum solution there by reprecipitating the sodium oleate as alum- Evi sis

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inum trioleate which mixes with the basic aluminum soap already present forming a product somewhat less basic. An addition at this stage equivalent to about 82 pounds of AlJSOQ works well. After the addition, stirring and heating are continued for a time to complete the reactions. If the desired equivalent basicity of the aluminum soap is now attained. the precipitation may be completed by adding excess alum solution, and the pulp washed, dried, and diluted ashereafter explained. But, since a greater pro portion of mono-aluminum soap in the mixture is usually desired, we next follow with another addition of caustic soda, this being added slowly, say, over a period of 1.5 to 2 hours. An addition of caustic equivalent to about 38 pounds of NaOH is useful. After completion of the addition of caustic solution,

digestion is continued until the mixture shows no free caustic. By this addition, sodium oleate is again re-formed at the expense of the aluminum tri-oleate which is reduced to the monoleate. Finally, we complete the operation by adding alum solution to complete precipitation. Aluminum sulfate equivalent to about 140 pounds is added, the addition extending over 2 hours. At this time, the aqueous portion of the batch will show a slightly acid reaction. lhe most desirable acidity is about pH 4.5.

In the operation ust described in substance there are a number of precipitations and reprecipitations, aluminum trioleate being converted into aluminum monoleate, and the sodium soap incidentally formed being reprecipitated as aluminum trioleate; the

amount of these actions decreasing as the process goes on. The final soaps resulting are largely a mixture of these two oleates. By modification in the quantities indicated, dioleates in greater proportion can be produced. It is, of course, understood that the proportions are given in pounds and gallons as referring to a certain sized batch; one using $50 pounds of cottonseed oil.

The material produced after the last addition of aluminum sulfate is, as stated, a pulp of thickened oil in a solution containing dissolved sodium sulfate and the glycerine of the original oil. vVhen this product is formed, the stirrer is stopped and the separated aqueous liquor is drawn off. Water is then added tov the pulp in the kettle and the whole heated, using both open and closed steam. Usually a jacketed kettle is employed. The'temperature is raised to near the boiling point of water and the pulp and hot water stirred together for a short time, say,"- about 20 minutes, when the stirrer is stopped and the water removed. More water is added and the operation repeated, and so cal on, until the wash water shows little or no sodium sulfate. Generallyo'or 6 washings are required. When washing is considered complete, the aqueous liquor is drained 0E from the pulp as completely as possible and the pulp dried by heating and stirring until it is nearly clear in appearance. tion of the operation requires considerable care to obtain the best results. To a considerable extent, the properties of the final product depend upon drying to the right degree of hydration or dehydration. Complete dehydration gives an oil of viscosity no higher than the mineral oil; insufficient drying causes thesoap to separate with production of cloudiness. Between these two extremes lies a very viscous pulp. When the pulp is dried to the desired extent, the heat is shut off and more mineral oil is added slowly with constant stirring, until a test shows the desired viscosity of commercial mineral castor oil has been,reached. With material made under the present invention, the viscosity shown in this test does not change materially on aging.

lhis portaining basic aluminum soaps as thickeners,

the process of preparing the thickener which comprises the steps of precipitating an aqueous solution of neutral fatty acid soap of an alkali with a suflicient quantity of a solution of an aluminum salt to convert said soap into a tri-acid soap of aluminum, then adding caustic alkali solution in amount sufficient to convert at least a portion of said tri-acid soap to a basic aluminum soap with production of neutral alkali soap, and then treating the re sultant mixture with a solution of aluminum salt in amount suflicient to react with said alkali soap to form aluminum tri-acid soap.

2. In preparing mineral castor oils containing basic aluminum soaps as thickeners, the process of preparing the thickener which comprises the steps of mixing an aqueous solution of a neutral fatty soap of alkali with a sufiicient quantity of a solution of an aluminum salt to convert said soap into tri-acid soap of aluminum and then addingcaustic alkali solution in amount sufiicient to convert at least a portion of said tri-acid soap to a basic -aluminum soap.

3. In preparing mineral castor oils containing basic aluminum soaps as thickenerfs,

the process of preparing the thickener which I I comprises the steps of mixing an aqueous solution of neutral fatty acid soda soap with a solution of aluminum sulfate in the proportions required to convert said soda soap into a tri-acid soap of aluminum, then adding caustic soda solution in amount sufficient to convert at least a portion of said tri-acid soap to a basic aluminum soap and then .adding further aluminum sulfate solution to reprecipitate the sodium soap formed by the caustic soda.

. 4. In preparing mineral castor oils containing basic aluminum soaps the process which comprises mixing anaqueous emulsion of a fatty acid soap of an alkali and lubricating oil with a sufficient quantity of a solution of aluminum salt to convert the said soap into a tri-acid soap of aluminum, then adding caustic alkali solution in amount suflicient to convert at: least a portion of said tri-acid soap to a basic aluminum soap with production of neutral alkali soap, then treating the resultant mixture with a solution of an aluminum salt in an amount suflicient to react with said alkali soap to form aluminum tri-acid soap, washing the mixture, drying the washed mixture by heat until it becomes nearly clear in appearance, and adding suflicient further lubricating oil to give a mineral castor oil of the viscosity desired.

5. In preparing mineral castor oils containing basic aluminum soaps the process which-comprises mixing anaqueous emulsion of a fatty acid soap of an alkali and lubricat-' ing oil with a sufficient quantity of a solution of aluminum salt to convert the said soap into a tri-acid soap of aluminum, then adding alkali solution suflicient to make the solution alkaline, then adding aluminum sulfate solution in amount 'sufiicient to make the mixture become acid in reaction, washing the pulpy mass thus produced, drying by heat until it becomes nearly clear in appearance, and adding further lubricating oil to produce a mineral castor oil of the viscosity desired.

6. The process of preparing a thickener for.

mineral castor oils which comprises making a basic aluminum soap and a less basic aluminum soap, and mixing to form a product of the desired fatty acidto aluminumratio.

' 7. In the manufacture of mineral castor oils containing basic aluminum soaps, the process which comprises emulsifying lubrieating oil with an aqueous solution of neutral soap, precipitating by addinga solution of an aluminum salt, whereby a precipitate of tri-acid aluminum soap is formed, then adding sufficient caustic alkali solution to correspond to two-thirds of the fatty acid in said tri-acid aluminum soap, thereby forming a solution of alkali'soap, adding a solution of an aluminum salt to re-produce aluminum soap at the expense of said alkali soap, thereby forming a mixture of soaps of different basicities, Washing the mixture, drying the mixture by heat until it is nearly clear in appearance, and adding further lubricating oil to produce the viscosity desired.

In testimony whereof we have hereunto affixed our signatures at the places and on the dates indicated.- 1

' Signed at Port Arthur, in the county of Jefi'erson 'and State of Texas, this 18th day of March, 1926.

. ROBERT WV. HENRY.

I Signed at Bayonne, in the county of Hudson and State of New J ersey, this 22nd of March, 1926.

ELF 0RD D. STREETER.

CERTHFWATE @F CQDRREETKQUN.

Paztem Na). mmz. Granted Nqwember H3, 1%, firm- .nammmw. ET AL.

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M. J. Mam-e, (Seal) Acting Commissinner 0% Patents; 

